Excellent book written in a lucid language. The book has simple exercises which make it interesting and also contains simple but effective techniques that can be easily implemented.
As rightly mentioned by the author in very first chapter, concentration is a skill which has to be learnt and practiced. It's also a wilful act and cannot be learnt unless you yourself are willing to learn.
In order to get effective results, one may have to read the book a few times and practice the exercises and techniques sincerely. However, after going through the initial chapters itself I am confident that this book can be extremely helpful to the parents, teachers, students and everyone who is sincerely interested in improving concentration and is willing to put in some amount of efforts in that direction.
Buying this book is an investment and not an expense.
My best wishes to the authors.